I have an idea of a rather vague chronology where the Burgundian Valois along the XVth century unified by dynastic union and conquest Burgundy, France and the Holy Empire. A bit like the house of Habsburg.
The goal would not be to present a monolithic Empire but rather a kind of loose Union and its impact on Europe. The religious and political schisms would be interesting to see in this universe.
I also have some related ideas that would fit in this universe:
-An earlier but much slower discovery of America.
-A reduced Ottoman Empire, the Byzantine Empire saved for a while and the end of the Great Schism.
-The absence of the Mughal Empire.
These are still very vague ideas and as I don't know the period well enough yet I don't think I'll write about it further.
Otherwise in general I am becoming more and more interested in the POD between the beginning of the 16th and the beginning of the 18th century.